Heat exchanger and cooling apparatus



June 7, 1966 FERGUSON 3,254,707

HEAT EXCHANGER AND COOLING APPARATUS Filed March 19, 1964 2 Sheets-Sheet1 F1 2. 78 6G 74 76 I 8 INVENTOR K5 NNETH F. FERGUSON BY H15 ATTORNEYS.HARE/S, mach; RUSSELL 62 Kamv June 7,1966 K. F. FERGUSON HEAT EXCHANGERAND COOLING APPARATUS 2 Sheets-Sheet 2 Filed March 19, 1964 Figlallllllllllll I rlllllllllllll INVENTOR.

KENNETH F. FERGUSON BY HIS HTTORNEY6. HARRIS, K/ECH, RussEu & KERNUnited States Patent 3 254 707 HEAT EXCHANGER AND COOLING APPARATUSKenneth F. Ferguson, Placentia, Calif., assignor to Hunt Foods andIndustries, Inc., Fullerton, Calif., 21. corporation of Delaware FiledMar. 19, 1964, Ser. No. 353,066 14 Claims. (Cl. 165-110) Primary objectsof the invention are to provide a cooling apparatus for use with aninternal combustion engine which is extremely effective in extractingheat from the water, or other coolant, used to cool the engine, andwhich efiiciently removes air, or other gases, and vapors from the waterso that these will not interfere with effective cooling of the engine.

Considering the manner in which the invention achieves the :foregoingbasic goals, an important object is to provide a heat exchanger, servingas a radiator in this in stance, which achieves extremely uniformdistribution of the water, or other coolant.

More particularly, an important object of the invention is to providemeans in the inlet and outlet headers of the heat exchanger forachieving uniform flow distribution throughout the core of the heatexchanger, which core may be of any suitable construction.

Still more particularly, an important object is to provide flowdistribution means comprising inlet and outlet ducts, disposed in theinlet and outlet headers, respectively, which are of steppedconstruction transversely of the heat exchanger and which .decreaseuniformly in area in a step-bystep manner from one side of the heatexchanger to the other, the inlet duct having inlet openings ofsubstantially equal size at the respective steps therein and the outletduct similarly having outlet openings of substantially equal size at therespective steps therein. With this construction, water is introducedinto the inlet header at a plurality of transversely spaced points andis Withdrawn from the outlet header at a plurality of transverselyspaced points, the rates of water introduction and withdrawal-at therespective points being substantially equal. The result is uniform flowof water through all parts of the heat exchanging core of the heatexchanger, this result being further enhanced by providing relativelylarge clearances around the inlet and outlet ducts Within the inlet andoutlet headers.

Considering the manner in which gases and vapors are removed from thewater to promote more effective engine cooling, an important object ofthe invention is to continuously circulate a fraction of the coolingWater through a reservoir adjacent and in fluid communication with theinlet header of the heat exchanger.

Another object is to achieve the foregoing by providing interconnectingports between the inlet header and the adjacent reservoir, and byconnecting the reservoir to the cooling water system of the engine onthe inlet side of the water pump thereof, the flow capacity of thisconnection being such as to constantly circulate a small fraction of thetotal cooling water flow from the inlet header through the adjacentreservoir to the water pump.

Another object in the [foregoing connection is to provide baflle meansat the ends of certain of the steps of the inlet duct in the inletheader for directing the water introduced into the inlet header towardthe ports connecting the inlet header to the reservoir thercadjacent.

The toregoing construction provides an extremely effective deaeratingmeans tor continuously bleeding off air, or other gases, and vapors intothe reservoir adjacent the inlet header. Such gases and vaporsaccumulate in the reservoir so that they cannot interfere with eificientcooling of the engine, which is :an important feature of the invent-ion.

Other objects are to provide a heat exchanger having headers which areoriented horizontally with the inlet header above the outlet header andwith the reservoir surmounting the inlet header, and to provide a heatexchanger having horizontally spaced, preferably vertical, headers withthe reservoir alongside the inlet header.

The foregoing objects, advantages, features and results of the presentinvention, together with various other objects, advantages, features andresults thereof which will be evident to those skilled in the art towhich the invention relates in the light of this disclosure, may beachieved with the exemplary embodiments of the inven tion described indetail hereinafter and illustrated in the accompanying drawings, inwhich:

FIG. 1 is a semidiagrammatic side elevational view showing oneembodiment of the cooling apparatus of the invention connected to thecooling water system or cooling means of an internal combustion engine;

FIG. 2 is a vertical sectional view taken as indicated by the arrowedline 22 of FIG. 1;

FIGS. 3, 4, 5 and 6 are enlarged, fragmentary sectional viewsrespectively taken along the arrowed lines 33, 44, '55 and 6-6 of FIG.2;

FIGS. 7 and 8 are [fragmentary sectional views respectively taken alongthe arrowed lines 77 and 8-8 of FIGS. 5 and 6;

FIG. 9 is a vertical sectional view of another embodiment of the coolingapparatus of the invention; and

FIGS. 10 and 11 are enlarged, fragmentary sectional views respectivelytaken along the arrowed line s '10-10 and 1:1- 1 1 of FIG. 9 of thedrawings.

Embodiment b FIGS. 1 t0 8 Referring initially to FIG. 1, designateddiagrammatically therein is an internal combustion engine 10 having theusual cooling water jacket through which water is circulated by a Waterpump I12. As is conventional, as long as the water temperature is belowa predetermined value, circulation by the pump s12 is confined to thewater jacket of the engine I10 by a thermostat (14. When the Watertemperature reaches the value for which the thermostat 14 is designed,the water may flow trom the water jacket of the engine through a line 16to a cooling apparatus 18 of the invention, returning through a line 20.As is conventional, the lines 16 and 20 are connected into the coolingwater system of the engine 10 on the outlet and inlet sides,respectively, of the pump 12. Since the foregoing structure, except [forthe cooling apparatus 18 of the invention, is conventional, furtherillustration and description are not necessary.

The cooling apparatus :18 includes a heat exchanger 24 which serves as aradiator in this instance. As is conventional, the radiator 24 ismounted in front of the engine 710 in a position to have air forcedtherethrough by the lforward motion of a vehicle, not shown, in whichthe engine may be mounted and/or by an engine-driven fan, not shown,located irearwardly of the radiator.

Considering the radiator 24 in more detail, it includes upper and lowertransverse horizontal headers 26 and 28 interconnected by a heatexchanging vertically oriented,

vertically extending core 30 of any suitable construction, which maycomprise the finned tubes shown. As thus far described, the radiator 24,with its combination of headers 26 and 28 and core 60, is more or lessconventional. The invention embodied in the radiator 24 will now beconsidered.

Disposed in the upper and lower headers 26 and 28, and extendingtransversely of the radiator 24 therein, are inlet and outlet ducts 436and 38, respectively. The inlet and outlet ducts 36 and 38, which extendsubstantially from one side of the radiator 24 to the other in therespective headers 26 and 28, are proveded with ends 40 and 9 42respectively connected to the lines 16 and 20 leading to the coolingwater system of the engine 10.

As best shown in FIG. 4, the headers 26 and 28 are relatively large incross section compared to the ducts 36 and 38 therein, thereby providingsubstantial clearances around the ducts. Such clearances contribute touniform water flow through the core 39 and to the removal of gases andvapors from the Water. More particularly, the sizeable clearance aroundthe inlet duct 36 insures that the water entering the radiator 24 canreach all portions of the core 30. The substantial clearance between theoutlet duct 38 and the bottom of the lower header 28 also serves as asediment .trap. If desired, access to the sediment trap may be providedin a manner not specifically shown to permit sediment removal.

As best shown in FIG. 2 of the drawings, the inlet duct 36 is of steppedconstruction and decreases in cross sectional area step by step from theinlet end 40 thereof to its opposite end. Similarly, the outlet duct 38is of stepped construction transversely of the radiator 24 and decreasesin cross sectional area step by step from the outlet end 42 thereof toits other end. The steps of each of the ducts 36 and 38 aresubstantially uniformly distributed across the width of the radiator 24,and the area reductions at the respective steps are substantially equal.(As viewed in FIG. 2 of the drawings, the left end of each duct :36 and38 may be regarded as a step which reduces the area to zero.)

The inlet duct 36 is provided with inlet openings 46 at the respectivesteps therein (including the last step defined by the left end of theduct 36, as viewed in FIG. 2). Similarly, the outlet duct 38 is providedwith outlet openings 48 at the respective steps therein (again includingthe last step defined by the left end of the duct 38, as viewed in FIG.2 of the drawings). The inlet openings 46 leading from the inlet duct 36into the upper header 26 are all substantially the same size, as are theoutlet openings 48 leading from the lower header 28 into the outlet duct38. This insures uniform distribution of the Water introduced into theupper header 26, and uniform withdrawal of water from the lower header28. Consequently, the flow of water through the core 30 from the upperheader 26 to the lower header 28 is also uni-form.

Thus, the heat exchanging core 30 operates with maximum effectiveness,as compared to prior radiators which permit channeling of the waterthrough only a portion or portions of the core. The end result is amplecooling capacity for the engine 10 Without an excessively largeradiator, excessive fan power losses, and the like.

The inlet duct 36 comprises simply a circular tube having the desiredsteps out therein and covered with plates 52 welded to the tube. As bestshown in FIGS. 5 and 7, the plates '52 are provided at their upstreamends with tongues 54 which project into the tube in the upstreamdirection. As will be apparent [from FIG. 7, each tongue 54 cleanlydivides the corresponding portion of the Water flow from the main streamcoursing through the inlet duct 36, and delivers it to the correspondinginlet opening 46.

All but the last plate 52 in the series are provided at their downstreamends with upturned baffles 56, subtending arcs of substantially 90, fordeflecting upwardly the streams of water emanating from the respectiveinlet openings 46 upstream therefrom. The last plate 52 in the series isnot provided with one of the baffles 56 since the adjacent end wall ofthe upper header 26 performs the same function. The upward motionimparted to the water by the battles 56, and by the end wall of theupper header 26 at the downstream end of the inlet duct 36, serves apurpose which will be discussed hereinafter.

The construction of the outlet duct 38 is similar to that of the inletduct 36, the outlet duct comprising a circular tube having steps cuttherein which are covered by plates 58 welded to the. tube. The plates58 are provided at their downstream ends with notches 60 which formparts of the outlet openings 48 leading from the outlet header =28 intothe outlet duct 38, thus providing these openings with relatively largeareas to minimize flow resistance.

Turning now to a consideration of the hereinbeforementioned means of theinvention for removing gases and vapors from the water circulatedthrough the radiator 24 by the pump 12, the upper header 26 issurmounted by a reservoir 66 which is separated from the upper header bya wall 68 common .to both. This common wall is provided therethroughwith ports 70 establishing fluid communication between the upper header26 and the reservoir 66.

The reservoir 66 is connected to the cooling water system of the engine10 on the inlet side of the pump 12 by a line 72 having a capacity ofthe order of, for example, ten percent of the capacity of the pump.Consequently, a small fraction of the water introduced into the upperheader 26 is continuously drawn upwardly into the reservoir 66 andthence back in to the cooling water system of the engine 10 through theline 72.

The foregoing construction provides very effective separation of gasesand vapors from the water circulating through the cooling water systemof the engine 10 and through the cooling apparatus '18. Gases and vaporstend to become separated from the heated water entering the upper header26, and are drawn upwardly into the reservoir 66 as the result of thebleeding of water from the reservoir through the line 72. Suchseparating out of the gases and vapors, and such withdrawal thereofupwardly into the reservoir 66, are enhanced by the action of thebaffles 56 in directing the heated water upwardly toward the top of theupper header 26 as it is introduced thereinto through the inlet openings46 in the inlet duct 36. The gases and vapors then accumulate in a layer74 at the top of the reservoir 66, where they cannot interfere witheflicient cooling of the engine 10.

The reservoir 66 serves additional functions, one being to provide a wayof filling the entire system with water. For this purpose, the reservoir66 is provided with a filler neck 76 which is closed by a cap 78,preferably a conventional pressure cap. As is conventional, an overflowline 80 leads from the filler neck. The reservoir 66 is located at anelevation such that the water level therein is above the highest pointin the cooling water jacket of the engine 10. Thus, the reservoir 66insures that the cooling water jacket of the engine 10 is alwayscompletely full to prevent hot spots.

As shown in FIG. 1 of the drawings, the reservoir 66 is also connectedto the cooling water system of the engine 10 below the thermostat 14 bya line 82 having a relatively small capacity. With this construction, asmall quantity of water can flow from the cooling water system of theengine, from a point below the thermostat 14, at all times, beingreplenished by water drawn through the line 72. The purpose of thisarrangement is to permit accumulations of gases or vapors below thethermostat 14, when the thermostat is closed, to be discharged into thereservoir 66. Thus, such accumulations of the gases or vapors cannotinterfere with efiicient engine cooling.

In the foregoing embodiment of FIGS. 1 to 8 of the drawings, the fiow isvertical from the upper, inlet header 26 to the lower, outlet header 28.However, the invention may be embodied in a heat exchanger which is sooriented that the flow from the inlet header to the outlet header ishorizontal, with the heat exchanger oriented either horizontally orvertically. The latter orientation is embodied in the species of theinvention which is illustrated in FIGS. 9 and 11 and which will now beconsidered.

Embodiment of FIGS. 910 11 Referring to FIG. 9, illustrated therein is acooling apparatus 118 of the invention which is similar to the apparatus18 and which may be regarded as corresponding approximately to theapparatus 18 rotated in the clockwise direction as the apparatus 18 isviewed in FIG. 2 of the drawings. In view of the fact that the coolingapparatus 118 is similar to the apparatus 18, the various components ofthe apparatus 118 will be identified by reference numerals higher by onehundred than the corresponding components of the apparatus 18.

Thus, the cooling apparatus 118 includes a heat exchanger 124 havingvertical inlet and outlet headers 126 and 128 connected by a verticallyoriented, horizontally extending core 130. Extending upwardly within theinlet and outlet headers 126 and 128 are stepped inlet and outlet ducts136 and 138, these having inlet and return lines 116 and 120 connectedto their respective lower ends 140 and 142. Exceptfor their verticalorientations, the inlet and outlet ducts 136 and 138 are identicalto'the inlet and outlet ducts 36 and 38, the relationships to the inletand outlet headers 126 and 128 also being substantially identical. Thus,a further description is not necessary, except to point out that theinlet duct 136 is provided with baffles 156 corresponding to the baffles56, but directed horizontally toward a reservoir 166 alongside the inletheader 126, instead of being directed upwardly as in the previousembodiment.

The reservoir 166 is separated from the inlet header 126 by an uprightwall 168 which is inclined toward the core 130. This inclined wall isprovided with a plurality of vertically spaced, horizontal slots 1'70therethrough, including one which interconnects the extreme upper endsof the inlet header 126 and the reservoir 166. The slots 170 below theuppermost one are provided thereabove with battles 171 which slopedownwardly toward the inlet duct 36 above the respective baffles 156thereon.

It will be apparent that, with the foregoing construction, any gases orvapors discharged into the inlet header 126 through the openings in theinlet duct 136 tend to rise along the inclined wall 168 and to passthrough the ports 170 into the reservoir 166. Such migration of thegases and vapors into the reservoir 166 is aided by the interactionbetween the baflles 171 and the baffles 156, and also by the fact thatthe wall 168 slopes toward the core 130 in the manner shown.Furthermore, a fraction of the total flow into the inlet header 126 isconstantly drawn oil through a line 172 corresponding to the line 72,thereby insuring migration of most of the gases and vapors from theinlet header 126 into the reservoir 166. Such gases and vapors thusaccumulate in the upper end of the reservoir 166 to prevent interferencewith effective heat exchange. Any gases and vapors tending to accumulatein the upper end of the outlet header 128 may pass to the upper end ofthe reservoir 166 through a connecting line 174.

The reservoir 166 is provided at its upper end with a filler neck 176adapted to be closed by a cap 178 and equipped with an overflow line180. A line 182, corresponding to the line 82, is also connected to thereservoir 166 for the same purpose as the line 82.

Although exemplary embodiments of the invention have been disclosedherein for purposes of illustration, it will be understood that variouschanges, modifications and substitutions may be incorporated in suchembodiments without departing from the spirit of the invention asdefined by the claims which follow.

I claim:

1. In combination:

'(a) a heat exchanger having spaced headers which extend transversely ofsaid heat exchanger;

(b) inlet and outlet duct which are disposed in said headers,respectively, and which extend transversely of said heat exchangertherein;

(c) each of said ducts being of stepped construction transversely ofsaid heat exchanger and decreasing uniformly in area step by step fromone side of said heat exchanger to the other; and

(d) each of said ducts having openings of uniform size at the ends ofthe respective steps therein and facing in the same direction.

2. In combination:

(a) a heat exchanger having horizontal upper and lower headers whichextend transversely of said heat exchanger;

(b) inlet and outlet ducts which are disposed in said upper and lowerheaders, respectively, and which extend transversely of said heatexchanger therein;

(0) each of said ducts being of stepped construction transversely ofsaid heat exchanger and decreasing uniformly in area step by step fromone side of said heat exchanger to the other; and

(d) each of said ducts having openings of uniform size at the ends ofthe respective steps therein and facing in the same direction.

3. In combination:

(a) a heat exchanger having vertical inlet and outlet headers whichextend transversely of said heat exchanger;

(b) inlet and outlet ducts which are disposed in said inlet and outletheaders, respectively, and which extend transversely of said heatexchanger therein;

(c) each of said ducts being of stepped construction transversely ofsaid heat exchanger and decreasing uniformly in area step by step fromone side of said heat exchanger to the other; and

(d) each of said ducts having openings of uniform size at the ends ofthe respective steps therein and facing in the same direction.

4. In combination:

(a) a heat exchanger having horizontal upper and lower headers whichextend transversely of saidheat exchanger;

(b) inlet and outlet ducts which are disposed in said upper and lowerheaders, respectively, and which extend transversely of said heatexchanger therein;

(c) each of said ducts being of stepped construction transversely ofsaid heat exchanger and decreasing uniformly in area step by step fromone sideof said heat exchanger to the other;

(d) each of said ducts having openings of uniform size at the ends ofthe respective steps therein and facing in the same direction; and

(e) 'baflle means for directing upwardly in said upper header fluiddischarged from at least some of said openings in said inlet duct.

5. In combination:

(a) a heat exchanger having horizontal upper and lower headers whichextend transversely of said heat exchanger;

(b) inlet and outlet ducts which are disposed in said upper and lowerheaders, respectively, and which extend transversely of said heatexchanger therein;

(c) each of said ducts being of stepped construction transversely ofsaid heat exchanger and decreasing uniformly in area step by step fromone side of said heat exchanger to the other;

(d) each of said ducts having openings of uniform size at the ends ofthe respective steps therein and facing in the same direction; and

(e) batlle means at the ends of certain of said steps of said inlet ductfor directing upwardly in said upper header fluid discharged from atleast some of said openings in said inlet duct.

6. In combination:

(a) a heat exchanger having inlet and outlet headers which extendtransversely of said heat exchanger;

(b) inlet and outlet ducts which are disposed in said 7 at the ends ofthe respective steps therein and facing in the same direction;

(f) a reservoir adjacent said inlet header; and

(f) port means interconnecting said reservoir and said inlet header influid communication.

7. In combination:

(a) a heat exchanger having inlet and outlet headers which extendtransversely of said heat exchanger; (b) inlet and outlet ducts whichare disposed in said inlet and outlet headers, respectively, and whichextend transversely of said heat exchanger therein;

(c) each of said ducts being of stepped construction transversely ofsaid heat exchanger and decreasing uniformly in area step by step fromone side of said heat exchanger to the other;

((1) each of said ducts having openings of uniform size at the ends ofthe respective steps therein and facing in the same direction;

(e) baflle means for directing upwardly in said upper header fluiddischarged from at least some of said openings in said inlet duct;

(f) a reservoir adjacent said inlet header; and

(g) port means interconnecting said reservoir and said inlet header influid communication.

8. In combination:

(a) a heat exchanger having upper and lower headers which extendtransversely of said heat exchanger; (b) inlet and outlet ducts whichare disposed in said upper and lower headers, respectively, and whichextend transversely of said heat exchanger therein;

() each of said ducts being of stepped construction transversely of saidheat exchanger and decreasing uniformly in area step by step from oneside of said heat exchanger to the other;

(d) each of said ducts having openings of uniform size at the ends ofthe respective steps therein and facing in the same direction;

(e) a reservoir surmounting said upper header; and

(f) port means interconnecting said reservoir and said upper header influid communication.

9. In combination:

(a) a heat exchanger having upper and lower headers which extendtransversely of said heat exchanger;

(b) inlet and outlet ducts which are disposed in said upper and lowerheaders, respectively, and which extend transversely of said heatexchanger therein;

(c) each of said ducts being of stepped construction transversely ofsaid heat exchanger and decreasing uniformly in area step by step fromone side of said heat exchanger to the other;

(d) each of said ducts having openings of uniform size at the ends ofthe steps therein and facing in the same direction;

(e) baffle means for directing upwardly in said upper header fluiddischarged from at least some of said openings in said inlet duct;

(f) a reservoir surmounting said upper header; and

(g) port means interconnecting said reservoir and said upper header influid communication.

10. In an apparatus for removing heat from an internal combustion enginehaving cooling means which includes a coolant jacket and a pump forcirculating a coolant through said jacket, the combination of:

(a) a radiator having upper and lower headers which extend transverselyof the radiator;

(b) inlet and outlet ducts which are disposed in said upper and lowerheaders, respectively, and which extend transversely of said radiatortherein;

(0) means for connecting said inlet and outlet ducts to said enginecooling means on the outlet and inlet sides, respectively, of said pump;

(d) said connecting means being connectible to said inlet and outletducts at one side of said radiator;

(e) each of said ducts being of stepped construction transversely ofsaid radiator and decreasing uniformly in area step by step from saidone side of said radiator to the other;

(f) each of said ducts having openings of uniform size at the endsof therespective steps therein and facing in the same direction;

(g) baflle means for deflecting upwardly in said upper header coolantdischarged from at least some of said openings in said inlet duct;

(h) a reservoir surmounting said upper header;

(i) port means interconnecting said reservoir and said upper header incoolant communication; and

(j) means for connecting said reservoir to said engine cooling means onthe inlet side of said pump.

11. In an apparatus for removing heat from an internal combustion enginehaving cooling means which includes a coolant jacket and a pump forcirculating a coolant through said jacket, the combination of:

(a) a radiator having inlet and outlet headers which extend transverselyof said radiator;

(b) inlet and outlet ducts which are disposed in said inlet and outletheaders, respectively, and which extend transversely of said radiatortherein;

(0) means for connecting said inlet and outlet ducts to said enginecooling means on the outlet and inlet sides, respectively, of said pump;

((1) said connecting means being connectible to said inlet and outletducts at one side of said radiator; (e) each of said ducts decreasing inarea from said one side of said radiator to the other;

(f) each of said ducts having openings therein at points spaced aparttransversely of said radiator, which openings are of uniform size andface in the same direction;

g) a reservoir adjacent said inlet header;

(h) port means interconnecting said reservoir and said inlet header incoolant communication; and

(i) means for connecting said reservoir to said engine cooling means onthe inlet side of said pump.

12. In an apparatus for removing heat from an internal combustion enginehaving cooling means which includes a coolant jacket and a pump forcirculating a coolant through said jacket, the combination of:

(a) a radiator having upper and lower headers which extend transverselyof said radiator;

(b) inlet and outlet ducts which are disposed in said upper and lowerheaders, respectively, and which extend transversely of said radiatortherein;

(c) means for connecting said inlet and outlet ducts to said enginecooling means on the outlet and inlet sides, respectively, of said pump;

(d) said connecting means being connectible to said inlet and outletducts at one side of said radiator;

(e) each of said ducts decreasing in area from said one side of saidradiator to the other;

(f) each of said ducts having openings therein at points spaced aparttransversely of said radiator, which openings are of uniform size andface in the same direction;

(g) a reservoir surmounting said upper header;

(h) port means interconnecting said reservoir and said upper header incoolant communication; and

(i) means for connecting said reservoir to said engine cooling means onthe inlet side of said pump.

13. In combination:

(a) a heat exchanger having a transversely extending header;

(in) a uniformly stepped duct disposed in said header and extendingtransversely of said heat exchanger; and decreasing uniformly in areastep by step from one side of said heat exchanger to the other; and

(c) said duct having openings of uniform size at the ends of therespective steps thereof and facing in the same direction.

14. In combination:

(a) a heat exchanger having a transversely extending,

generally horizontal header;

(b) a generally horizontal, uniformly stepped duct disposed in saidheader and extending transversely of said heat exchanger and decreasinguniformly in area step by step from one side of said heat exchanger tothe other;

(c) said duct having openings of uniform size at the ends of therespective steps thereof and facing in the same direction;

(d) said duct having upturned baflles at certain of said steps,respectively; and

(e) said baffles being located opposite and in the paths of flow fromcertain of said openings, respectively.

References Cited by the Examiner UNITED STATES PATENTS Bolton 165174 XClark 165174 Rushmore 165--1l0 Conpland 165174 Anderegg 165110 Ware etal. 165174 Evans et al. 165111 Walton 16551 JAMES W. WESTHAVER, PrimaryExaminer.

1. IN COMBINATION: (A) A HEAT EXCHANGER HAVING SPACED HEADERS WHICHEXTEND TRANSVERSELY OF SAID HEAT EXCHANGER; (B) INLET AND OUTLET DUCTSWHICH ARE DISPOSED IN SAD HEADERS, RESPECTIVELY, AND WHICH EXTENDTRANSVERSELY OF SAID HEAT EXCHANGER THEREIN; (C) EACH OF SAID DUCTSBEING OF STEPPED CONSTRUCTION TRANSVERSELY OF SAID HEAT EXCHANGER ANDDECREASING UNIFORMLY IN AREA STEP BY STEP FROM ONE SIDE OF SAID HEATEXCHANGER TO THE OTHER; AND (D) EACH OF SAID DUCTS HAVING OPENINGS OFUNIFORM SIZE AT THE ENDS OF THE RESPECTIVE STEPS THEREIN AND FACING INTHE SAME DIECTIONS.